This invention relates to electrostatographic reproduction machines, and more particularly to an economical and capacity-extendible all-in-one process cartridge for easy adaptive use in a family of compact electrostatographic reproduction machines having different volume capacities and consumable life cycles. Specifically this invention relates to such a cartridge including a printing cartridge with a molded cantilever developer roller spacing spring.
Generally, the process of electrostatographic reproduction, as practiced in electrostatographic reproduction machines, includes charging a photoconductive member to a substantially uniform potential so as to sensitize the surface thereof. A charged portion of the photoconductive surface is exposed at an exposure station to a light image of an original document to be reproduced. Typically, an original document to be reproduced is placed in registration, either manually or by means of an automatic document handler, on a platen for such exposure.
Exposing an image of an original document as such at the exposure station, records an electrostatic latent image of the original image onto the photoconductive member. The recorded latent image is subsequently developed using a development apparatus by bringing a charged dry or liquid developer material into contact with the latent image. Two component and single component developer materials are commonly used. A typical two-component dry developer material has magnetic carrier granules with fusible toner particles adhering triboelectrically thereto. A single component dry developer material typically comprising toner particles only can also be used. The toner image formed by such development is subsequently transferred at a transfer station onto a copy sheet fed to such transfer station, and on which the toner particles image is then heated and permanently fused so as to form a "hardcopy" of the original image.
It is well known to provide a number of the elements and components, of an electrostatographic reproduction machine, in the form of a customer or user replaceable unit (CRU). Typically such units are each formed as a cartridge that can be inserted or removed from the machine frame by a customer or user. Reproduction machines such as copiers and printers ordinarily include consumable materials such as toner, volume limiting components such as a waste toner container, and life cycle limiting components such as a photoreceptor and a cleaning device. Because these elements of the copying machine or printer must be replaced frequently, they are more likely to be incorporated into a replaceable cartridge as above.
There are therefore various types and sizes of cartridges, varying from single machine element cartridges such as a toner cartridge, to all-in-one electrostatographic toner image forming and transfer process cartridges. The design, particularly of an all-in-one cartridge can be very costly and complicated by a need to optimize the life cycles of different elements, as well as to integrate all the included elements, while not undermining the image quality. This is particularly true for all-in-one process cartridges to be used in a family of compact electrostatographic reproduction machines having different volume capacities and elements having different life cycles.
There is therefore a need for a quality image producing, economical and capacity-extendible all-in-one process cartridge that is easily adapted for use in various machines in a family of compact electrostatographic reproduction machines having different volume capacities and elements with different life cycles.
The step of development or placing the toner particles in contact with the latent image on the photoconductor drum to form the developed image requires that the marking particles or toner be presented to the photoconductive drum. Typically, a donor roll or a roll including a stationary internal magnetic shaft with a rotatable aluminum steel positioned around the outer peripheral of the shaft is utilized to advance the marking particles toward the photoconductive drum.
The spacing between the developer roll and the photoconductive drum surface is important. Spacers placed on the developer roll are often used to ride against the photoconductive surface of the photoconductive drum to maintain an accurate distance between the developer roll and the photoconductive drum. To assure that the spacer remains in contact with the photoconductive surface of the photoconductive drum, preferably, the developer roll is pivotably positioned into contact with the photoconductive drum. A device, usually in the form of a spring, is used to urge the developer roll against the photoconductive drum.
To maintain the urging force of the developer roll against the photoconductive drum, springs typically in the form of a coil spring are positioned between the pivotable developer housing and the printing machine or a fixed printing or process cartridge within the printing machine. The use of this spring adds assembly costs to the printing machine or print cartridge in which the springs are located.
Further, the springs must be assembled into the developer cartridge and print cartridge requiring added cost. Also, the springs are small loose parts and may become dislodged from their desired position during assembly and these assembly errors may cost quality problems within the printing cartridge.
The following disclosures may be relevant to various aspects of the present invention:
U.S. Pat. No. 4,556,308 PA1 Patentee: Hoppner, et al. PA1 Issue Date: Dec. 3, 1985 PA1 U.S. Pat. No. 4,987,446 PA1 Patentee: Mochimaru, et al. PA1 Issue Date: Jan. 22, 1991 PA1 U.S. Pat. No. 5,581,325 PA1 Patentee: Yashiro PA1 Issue Date: Sep. 12, 1995 PA1 U.S. Pat. No. 4,556,308 discloses a process cartridge including a mounting device including a pair of locating pivot pins. Mounting hinge slots are in engagement with cartridge latch blocks. The latch blocks have arcuate slots and a curved outer deflectable cantilever spring arm. The spring arm provides an interference with the cartridge mounting pins and is deflected thereby providing a counterbalance to the cartridge. PA1 U.S. Pat. No. 4,987,446 discloses a process cartridge for use in a electrophotographic apparatus. The cartridge includes a charger and a cleaning unit which are mounted on the cartridge integrally with each other. PA1 U.S. Pat. No. 5,581,325 discloses a process cartridge including a first support member for supporting an image bearing member, a second support member for supporting a development unit and a compression spring for generating an elastic force between the image bearing member and the development unit.